Fire-extinguishing sheet

ABSTRACT

The present invention discloses a fire extinguishing sheet which is used in places, facilities, devices, tools, structures and the like where a fire may break out, and which makes initial fire extinguishing possible. This fire extinguishing sheet contains at least a potassium compound as a fire extinguishing chemical that is thermally decomposed upon reaching a predetermined temperature and generates a fire extinguishing component; and this fire extinguishing sheet is arranged in places, facilities, devices, tools, structures and the like where a fire may break out. If a fire breaks out, aerosols containing potassium radicals (a potassium compound) are generated from the fire extinguishing sheet, and the chain of combustion is interrupted by a negative catalytic effect, thereby quickly extinguishing or suppressing the fire.

TECHNICAL FIELD

The present invention relates to a fire-extinguishing sheet that canextinguish a fire in an early stage, and that is used for places,facilities, devices, tools, structures and the like where a fire maybreak out.

BACKGROUND ART

A fire-extinguishing composition to extinguish or suppress a fire bygenerating an aerosol by burning has been known (for example, PLT 1).The fire-extinguishing composition can be used as a liquid for adispersion body, or as a solid such as a powder or a formed articlehaving an intended shape.

CITATION LIST Patent Literature

-   PLT 1: WO20171134703

SUMMARY OF INVENTION Technical Problem

In the formed article described in PLT 1, which is so called aself-distinguishing formed article, there has still been a room forimprovement.

It is therefore an object of the present invention to provide afire-extinguishing sheet that can extinguish a fire in an early stage,and that is used for places, facilities, devices, tools, structures andthe like where a fire may break out.

Solution to Problem

According to the present invention, there is provided afire-extinguishing sheet comprising a fire-extinguishing agent capableof generating a fire-extinguishing component by thermal decompositionupon reaching a prescribed temperature.

According to a preferred embodiment of the present invention, thefire-extinguishing component is an aerosol.

According to one preferred embodiment of the present invention, thefire-extinguishing agent includes at least a potassium compound and abinding agent.

According to a preferred embodiment of the present invention, thepotassium compound comprises at least a potassium-containing organiccompound and potassium chlorate.

According to an embodiment of the present invention, the binding agentis preferably one, or two or more selected from the group consisting ofa polyester resin, polystyrene, a polyolefin resin, a polyurethaneresin, polyisocyanate, a polyimide resin, an acrylic resin, a cellulosecompound, vinyl chloride, an ethylene-vinyl acetate copolymer, apolyvinylidene fluoride resin, a fluorine resin binder, a syntheticlatex, a rosin, an epoxy resin, a phenol resin, a polyvinyl alcoholresin, a polyvinyl acetal resin, an olefinic thermoplastic resin, abutadiene thermoplastic resin, a styrene thermoplastic resin, astyrene-butadiene thermoplastic resin, an isoprene thermoplastic resin,a urethane thermoplastic resin, an ester thermoplastic resin, an amidethermoplastic resin, a vinyl chloride thermoplastic resin, athermoplastic resin formed of a mixture of a process oil, a tackifierresin, and the like, an alloy type thermoplastic elastomer, a dynamiccrosslinkable thermoplastic elastomer, bentonite, and biobinder biopolyB.

Also, according to a preferred embodiment of the present invention, thefire-extinguishing sheet comprises at least tripotassium citrate andpotassium chlorate as the potassium compound and at least polyvinylbutyral as the binding agent.

According to another embodiment of the present invention, there isprovided a fire-extinguishing sheet for use with a lithium ion battery,which comprises the fire-extinguishing sheet according to the presentinvention and which is used in contact with or adjacent to the lithiumion battery.

According to still another embodiment of the present invention, there isprovided use of the fire-extinguishing sheet according to the presentinvention for extinguishing or suppressing a fire of a lithium ionbattery.

Also, according to another embodiment of the present invention, there isprovided a method for extinguishing or suppressing a fire of a lithiumion battery, comprising putting the fire-extinguishing sheet accordingto the present invention in contact with or adjacent to the lithium ionbattery.

Advantages

According to the present invention, there is provided afire-extinguishing sheet that can extinguish a fire in an early stage,and that is used for places, facilities, devices, tools, structures andthe like where a fire may break out. The fire-extinguishing sheet isexcellent in productivity, mass productivity, and mass production.

DESCRIPTION OF EMBODIMENT

Hereinafter, the fire-extinguishing sheets according to representativeembodiments of the present invention will be explained in detail.

The fire-extinguishing sheet according to the present invention includesa fire-extinguishing agent which is capable of generating afire-extinguishing component by thermal decomposition upon reaching aprescribed temperature. According to one embodiment of the presentinvention, the fire-extinguishing sheet is the fire-extinguishing agentthat is formed in a sheet-like shape. The fire-extinguishing sheetgenerates an aerosol as the fire-extinguishing component. Thefire-extinguishing sheet includes at least a potassium compound and abinding agent in the fire-extinguishing agent.

According to one embodiment of the present invention, thefire-extinguishing agent includes, for example, 0.5% to 30% by mass of abinding agent (component A) and 10% to 70% by mass of a chlorate salt(component B), and further 30 to 900 parts by mass of a potassium salt(component C), relative to 100 parts by mass of the binding agent andthe chlorate salt; and in addition, the thermal decompositiontemperature of the fire-extinguishing agent is in the range of 90° C. orhigher to 450° C.

Examples of component A, i.e., the binding agent, preferably include apolyester resin, polystyrene, a polyolefin resin, a polyurethane resin,polyisocyanate, a polyimide resin, an acrylic resin, a cellulosecompound, vinyl chloride, an ethylene-vinyl acetate copolymer, apolyvinylidene fluoride resin, a fluorine resin binder, a syntheticlatex, a rosin, an epoxy resin, a phenol resin, a polyvinyl alcoholresin, a polyvinyl acetal resin, an olefinic thermoplastic resin, abutadiene thermoplastic resin, a styrene thermoplastic resin, astyrene-butadiene thermoplastic resin, an isoprene thermoplastic resin,a urethane thermoplastic resin, an ester thermoplastic resin, an amidethermoplastic resin, a vinyl chloride thermoplastic resin, athermoplastic resin formed of a mixture of a process oil, a tackifierresin, and the like, an alloy type thermoplastic elastomer, a dynamiccrosslinkable thermoplastic elastomer, bentonite, and biobinder biopolyB, as well as a mixture of two or more of them.

Component B, i.e., the chlorate salt, is a strong oxidant, and is thecomponent that generates a thermal energy by burning with component C,i.e., the potassium salt, which in turn generates an aerosol (potassiumradical). This aerosol releases a potassium radical (potassium compound)that is the fire-extinguishing component, which breaks up burning chainsdue to a negative catalytic effect thereof so that the fire can beextinguished quickly.

The contents of component A (binding agent) and of component B (chloratesalt) in 100% by mass of the total of them are as follows:

-   Component A: 0.5% to 30% by mass.    -   preferably 1% to 20% by mass,    -   more preferably 3% to 10% by mass; and-   Component B: 70% to 99.5% by mass.    -   preferably 80% to 99% by mass, and    -   more preferably 90% to 97% by mass.

Component C, i.e., the potassium salt, is the component to generate theaerosol (potassium radical) by a thermal energy generated by burning ofcomponent B.

Examples of component C, i.e., the potassium salt, preferably includepotassium acetate, potassium propionate, monopotassium citrate,dipotassium citrate, tripotassium citrate, monopotassium trihydrogenethylenediaminetetraacetate, dipotassium diihydrogenethylenediaminetetraacetate, tripotassium monohydrogenethylenediaminetetraacetate, tetrapotassium ethylenediaminetetraacetate,potassium hydrogen phthalate, dipotassium phthalate, potassium hydrogenoxalate, dipotassium oxalate, potassium hydrogen carbonate, andpotassium bicarbonate, as well as a mixture of two or more of them.

The content of component C is preferably 50 to 500 parts by mass, whilemore preferably 100 to 300 parts by mass, relative to 100 parts by massof component A and component B.

In the present invention, the fire-extinguishing agent starts thethermal decomposition in the temperature range of 90° C. or higher to450° C., while preferably in the range of 150° C. to 260° C. Thistemperature range to start the thermal decomposition can be obtained bycombining component A, component B, and component C with the ratiosabove.

The fire-extinguishing sheet according to the present invention isobtained by forming the fire-extinguishing agent in a formed articlesuch as a sheet. For example, the components of the fire-extinguishingagent are mixed; then, the resulting mixture is formed to a sheet-likeshape with controlling the coating condition, followed by drying asneeded. The size, such as the thickness and the area, of thefire-extinguishing sheet according to the present invention isdetermined as appropriate in accordance with an object forfire-extinguishing such as a facility, an instrument, a machine, a tool,and a construction structure, and with the use thereof, among otherthings. A laminate of a plurality of the sheet-like fire-extinguishingagents can also be used.

The fire-extinguishing sheet according to the present invention is usedby disposing in the place where the object of fire-extinguishment suchas a facility, an instrument, a machine, a tool, and a constructionstructure can possibly cause a fire. For example, in the case of theinstrument and the tool, the fire-extinguishing sheet is disposed incontact with or adjacent to a battery cell including a secondary batterysuch as a lithium ion battery that can cause a fire by some trouble suchas an unexpected accident, as well as a member that can cause a firesuch as a housing, an electrode, a communication terminal, and a circuitboard of the battery. The fire-extinguishing sheet may be disposed in aplurality of the places.

The fire-extinguishing sheet according to the present invention can besealed inside of an object such as a facility, an instrument, a machine,a tool, and a construction structure in order to expresses thefire-extinguishing action by means of the aerosol as mentioned above.Also, it can be sealed together with the member that can possibly causea fire, as described above.

EXAMPLES

The present invention will be explained more specifically with Examplesand Comparative Example. In these Examples and Comparative Example, thefire-extinguishing sheets were prepared in the way as describedfollowing (1).

(1) Preparation of Fire-Extinguishing Sheet

(1-1) Preparation of Binding Agent

Polyvinyl butyral as a binding agent was dissolved intoN-methylpyrrolidone, as a solvent, to obtain a 18% by mass solution ofpolyvinyl butyral.

(1-2) Preparation of Fire-Extinguishing Agent Slurry by Powder Crushing

Tripotassium citrate (187.5 g), 112.5 g of potassium chlorate, and 200 gof N-methylpyrrolidone, as well as 2 kg of alumina balls having thegrain diameter of 5 mm as the dispersion media, were charged into a2-liters container; then, they were stirred and crushed by means of aball mill at 60 rpm for about 24 hours to obtain a fire-extinguishingagent slurry.

(1-3) Preparing Coating Material (Addition of the Binding Agent into theFire-Extinguishing Agent Slurry)

To the entire of the fire-extinguishing agent slurry obtained in (1-2),111 g of the polyvinyl butyral solution with the concentration of 18% bymass obtained in (1-1) was added. The resulting mixture was furthermixed using the ball mill at 60 rpm for about 24 hours to obtain acoating material in a paste-like form (mayonnaise-like) having athixotropic property. The viscosity of the resulting coating materialwas confirmed to be in the range of 2000 to 3000 mPa·S using B-typeviscometer with load (torque) of 50%.

(1-4) Separation (Removal of Dispersion Media)

By using an appropriate metal strainer made of a stainless steel, thecoating material obtained in (1-3) and the dispersion media areseparated. It was confirmed that yield was in the range of 50 to 60%.

(1-5) Filtration (Separation of Coarse Agent and Foreign Matters)

The coating material obtained in the separation process in (1-4) wasfiltrated using a 100-mesh stainless steel sieve (opening of about 200μm) to remove coarse particles and foreign matters.

(1-6) Coating (Sheeting of the Coating Material)

A PET film having the thickness of 100 μm, having been treated with asilicon (Si) or fluorine (F) release film, was placed on the table of“β-coater”, manufactured by Yasui Seiki Inc.; then, on it was appliedthe fire-extinguishing agent slurry. Around type applicator having a gapof 400 μm was used for application. Application onto the PET sheet wascarried out with the application speed of about 0.5 mm/min.

(1-7) Drying Process (Removal of Solvent)

By using a general circulation type constant temperature oven, thesolvent was removed. The drying process was carried out at the settingtemperature of 100° C. under the state that the agent was coated on thePET film to obtain the sheet having the average thickness of 220 μm.

(1-8) Cutting Process

The agent under the state of being coated on the PET film was cooled,and then, this was cut out to the A4 size (horizontal 210 mm×vertical297 mm) to be used for the evaluation test.

(2) Evaluation Test of the Fire-Extinguishing Sheet

The fire-extinguishing sheet obtained in (1) was tested in the way asdescribed below.

(2-1) Placing of Lithium Ion Battery Cell

A 3 Ah lithium ion battery cell having the size of horizontal 100mm×vertical 100 mm×height 5 mm was placed in the center of a box-typecontainer made of SUS 304 with the plate thickness of 1.2 mm having thesize of horizontal 300 mm×vertical 300 mm×height 100 mm.

(2-2) Bonding of the Fire-Extinguishing Sheet

An acrylic plate having the size of horizontal 350 mm×vertical 350 mm×10mm with the plate thickness of 5 mm, having a hole with a diameter of 10mm in the center thereof, was used as the top board of the box-typecontainer in (2-1). In the center of one side of this acrylic plate, thefire-extinguishing sheet with the A4 size obtained in (1) was bonded byusing a spray paste.

(2-3) Fixing of the Acrylic Plate

The acrylic plate was fixed on the box-type container such that the sidebonded with the fire-extinguishing sheet was down.

(2-4) Nailing

An iron-made nail having a diameter of 5 mm was inserted into theopening of the acrylic top board at a constant rate to penetrate throughthe inner cell. At the moment of a short circuit, a flash was seen; butsoon, a white smoke was generated from the fire-extinguishing sheet, sothat the fire was extinguished without spreading.

COMPARATIVE EXAMPLE

In the evaluation test in (2), the evaluation test of the lithium ionbattery cell using the nail was carried out in the way as described in(2-4) without bonding the fire-extinguishing sheet with the A4 size of(2-2) onto the acrylic top board. The lithium ion battery in theSUS-made container was explosively burned to cause a fire, which wasspread in the entire container and continued for 5 minutes.

The representative embodiment of the present invention was describedabove, but the present invention is not limited to the above. Variousmodifications in the designing are possible, and these are also includedin the present invention.

1. A fire-extinguishing sheet comprising a fire-extinguishing agent which is capable of generating a fire-extinguishing component by thermal decomposition upon reaching a prescribed temperature.
 2. The fire-extinguishing sheet according to claim 1, wherein the fire-extinguishing component is an aerosol.
 3. The fire-extinguishing sheet according to claim 1, wherein the fire-extinguishing agent comprises at least a potassium compound and a binding agent.
 4. The fire-extinguishing sheet according to claim 3, wherein the potassium compound comprises at least a potassium-containing organic compound and potassium chlorate.
 5. The fire-extinguishing sheet according to claim 3, wherein the binding agent is one, or two or more selected from the group consisting of a polyester resin, polystyrene, a polyolefin resin, a polyurethane resin, polyisocyanate, a polyimide resin, an acrylic resin, a cellulose compound, vinyl chloride, an ethylene-vinyl acetate copolymer, a polyvinylidene fluoride resin, a fluorine resin binder, a synthetic latex, a rosin, an epoxy resin, a phenol resin, a polyvinyl alcohol resin, a polyvinyl acetal resin, an olefinic thermoplastic resin, a butadiene thermoplastic resin, a styrene thermoplastic resin, a styrene-butadiene thermoplastic resin, an isoprene thermoplastic resin, a urethane thermoplastic resin, an ester thermoplastic resin, an amide thermoplastic resin, a vinyl chloride thermoplastic resin, a thermoplastic resin formed of a mixture of a process oil, a tackifier resin, and the like, an alloy type thermoplastic elastomer, a dynamic crosslinkable thermoplastic elastomer, bentonite, and biobinder biopoly B.
 6. The fire-extinguishing sheet according to claim 3, wherein the potassium compound comprises at least tripotassium citrate and potassium chlorate, and the binding agent comprises at least polyvinyl butyral.
 7. A fire-extinguishing sheet for use with a lithium ion battery, which comprises the fire-extinguishing sheet according to claim 1 and which is used in contact with or adjacent to the lithium ion battery.
 8. The fire-extinguishing sheet for use with a lithium ion battery according to claim 7, wherein the sheet is used by bonding to the lithium ion battery.
 9. The fire-extinguishing sheet for use with a lithium ion battery according to claim 7, wherein the lithium ion battery is mounted on a facility, an instrument, a machine, a tool, or a construction structure.
 10. A facility, an instrument, a machine, a tool, or a construction structure, comprising a lithium ion battery and the fire-extinguishing sheet according to claim 1 which is in contact with or adjacent to the lithium ion battery.
 11. (canceled)
 12. A method for extinguishing or suppressing a fire of a lithium ion battery, comprising the step of putting the fire-extinguishing sheet according to claim 1 in contact with or adjacent to the lithium ion battery.
 13. The method according to claim 12, wherein the lithium ion battery is mounted on a facility, an instrument, a machine, a tool, or a construction structure.
 14. The method according to claim 12, wherein the fire-extinguishing component is an aerosol.
 15. The method according to claim 12, wherein the fire-extinguishing agent comprises at least a potassium compound and a binding agent.
 16. The method according to claim 15, wherein the potassium compound comprises at least a potassium-containing organic compound and potassium chlorate.
 17. The method according to claim 15, wherein the binding agent is one, or two or more selected from the group consisting of a polyester resin, polystyrene, a polyolefin resin, a polyurethane resin, polyisocyanate, a polyimide resin, an acrylic resin, a cellulose compound, vinyl chloride, an ethylene-vinyl acetate copolymer, a polyvinylidene fluoride resin, a fluorine resin binder, a synthetic latex, a rosin, an epoxy resin, a phenol resin, a polyvinyl alcohol resin, a polyvinyl acetal resin, an olefinic thermoplastic resin, a butadiene thermoplastic resin, a styrene thermoplastic resin, a styrene-butadiene thermoplastic resin, an isoprene thermoplastic resin, a urethane thermoplastic resin, an ester thermoplastic resin, an amide thermoplastic resin, a vinyl chloride thermoplastic resin, a thermoplastic resin formed of a mixture of a process oil, a tackifier resin, and the like, an alloy type thermoplastic elastomer, a dynamic crosslinkable thermoplastic elastomer, bentonite, and biobinder biopoly B.
 18. The method according to claim 15, wherein the potassium compound comprises at least tripotassium citrate and potassium chlorate, and the binding agent comprises at least polyvinyl butyral.
 19. The fire-extinguishing sheet for use with a lithium ion battery according to claim 12, wherein the putting step is performed by pasting the fire-extinguishing sheet on the lithium ion battery. 